Secretary of State Hillary Clinton paid tribute to slain U.S. Ambassador to Libya Chris Stevens, calling him a "fallen hero."

Stevens and three other Americans died in the attack two months ago.

Clinton praised the fallen diplomat for volunteering to serve in dangerous areas.

"He also knew when America is absent, especially from the dangerous places, there are consequences. Extremism takes root, our interests suffer, and security at home is threatened," Clinton said.

Stevens was given an international Common Ground award for conflict resolution and community and peace building. His sister, Anne Stevens, accepted the award on his behalf.

"Chris didn't shy away from high risk assignments in violence-affected places," she said. "He eagerly served in Jerusalem and Libya during times of conflict. He thought particularly in such complex political circumstances diplomacy could play a critical role by facilitating dialogue and bringing people together."

Stevens' death sparked intense partisan bickering and spawned three investigations, one from the State department, one from the FBI, and another from Congress.